This invention relates to a valve, and specifically to a safety discharge valve that can be used in the ballast tanks of submarines and oil platforms.
The inventor had disclosed a cabin-bottom valve in 2005 (Chinese Patent Application No. 200510045517.3). In the practical application the following weaknesses of the valve have been identified:
1. The middle part of the valve rod, as well as its upper part during the period when the valve is open, is exposed to the seawater in the cabin. The erosion of marine microorganisms and the accumulated attachment of marine shellfishes impose a serious risk for valve fault, sometimes even causing the valve unable to open or close. Additionally because of the simultaneous shutdown of the bottom valve port and the side valve port, seawater is retained in the valve chamber. This causes the shellfishes to attach on the valve rod and other internal parts and may ultimately lead to valve failure.
2. The valve plate is opened or closed by sliding vertically along the guide groove. Because the valve rod, tensioner, valve plate and guide plate are all connected to the pin bushing linkage structure, the valve is unable to shut down on occasions where any connection point of the linkage structure gets jammed or damaged when the valve rod moves up or when the closed valve needs to be opened.
3. On occasions where the opened valve needs to be closed, under a variety of deleterious situations such as human operational mistakes, failure of the open/close instruction on the valve driving mechanism, or disconnection between the valve and the driving mechanism, the bottom valve disc and the side valve plates cannot automatically move back to close the valve. This will cause the seawater to pour through the bottom port into the valve chamber, and further through the side port into the cabin, imposing a significant danger to the safety of submarines or oil platforms.
4. On occasions where the valve needs to shut down but fails so because foreign object obstruction occurs between the side valve plates and the side water inlets, the valve rod cannot move down due to its linkage with the tensioner and the side valve plates, which also causes the bottom valve disc not able to securely shut down the bottom valve outlet. This will cause the seawater to pour into the cabin and may lead to severe accidents.
5. On occasions where the valve needs to shut down but foreign object obstruction occurs between the bottom valve disc and the bottom water outlet, the valve rod cannot move down to carry the bottom valve disc to shut down the bottom water outlet. The side valve plates also cannot move down to shut down the side water inlets due to their linkage with the tensioner and the valve rod. This will cause the seawater to pour through the bottom outlet into the valve chamber, and further through the side water inlets into the cabin, imposing a significant danger to the safety of submarines or oil platforms.
6. On occasions where the valve cannot shut down because the foreign object obstruction occurs simultaneously between the bottom valve disc and bottom water outlet, and between the side valve plates and the side water inlets, the seawater will pour into the cabin in the absence of emergency plugging devices. This will cause ballast imbalance and may ultimately lead to oil platform capsizing.
7. On occasions where the valve bottom and the bottom valve disc are damaged due to accidental collision, the valve rod may be distortionally deformed. Because of the linkage structure of the valve, the deformed valve rod will result in failed sealing between the side valve plates and the side water inlets. This may cause the seawater to pour into the cabin.
Currently there have been no technical solutions to these potentially fatal flaws of this art.